Whilst many AS patients have problems that originate firstly in SI joint/s it is not necessary that all HLA B27 associated Spondylarthropathies start there. My problems started first as a chronic diarrohoea (IBS) then inflammation of the manubrio-sternal joint (considered part of the axial spine) but still have no involvment of the SI joints. Interestingly both the SI joints and the manubrio-sternal jounts are close to areas of bone-marrow - perhaps this is no coincidence and has something to do with the immune disruptive nature for the disease.
Cheers David P

Dx Oct 2006 B27+ undifferentiated spondlyarthropathy (uSpA) with mild sebhorrhoeic dermatitis and mild Inflammatory Bowel Disease (IBD) controlled by NSD since 2007.